Aminooxyacetic acid (AOA) as a plant growth inhibitor

ABSTRACT

A method of inhibiting plant height growth without having any significant impact on flowering, which comprises applying to the above ground portion of the plant at a point in time when the plant is beyond the seed leaf stage, and at least at approximately at the first true leaf stage, a small but growth inhibiting amount of aminooxyacetic acid.

BACKGROUND OF THE INVENTION

This invention relates to compositions and methods for controlling plantgrowth, particularly the growth of bedding plants. More particularly, itrelates to compositions and methods for controlling the height ofbedding plants.

It is desirable from time to time to control the height of beddingplants. The purchasing consumer does not necessarily regard a tall plantas aesthetically pleasing. It is, therefore, typical for commercialproducers to apply a growth regulator to inhibit bedding plants fromgrowing to an unusually tall size before they are sold. Typical of thegrowth regulators which have been used from time to time in the past areB-Nine (butanededic acid mono [2,2-dimethylethyldrazide]); A-Rest(alpha-cyclopropyl-alpha-[methoxyphenyl]-5- pyrmidinemethanol); Cycocel(2-[chloroethyl[trimethylammonium chloride); Florel (ethephon)(2-chloroethyl phosphonic acid).

While these prior art growth regulators all have some effect on someparticular bedding plants, they do not have widespread generalapplicability to all types of bedding plants, such as petunias,impatiens, geraniums, pansies, snapdragons, and ageratums. Moreover,many of the above referred to prior art growth regulators are onlyeffective for a short term delay in height growth, after which the plantcontinues growing taller. In addition, the activity of the abovereferred to prior art growth regulators commonly used for bedding plantsare often temperature-dependent as to their effectiveness. This isparticularly true for B-Nine.

Accordingly, it can be seen that there is a real and continuing need foran effective plant growth regulator of general applicability for beddingplants, which significantly delays, and in some cases actually stops,growth in height. This invention has as its primary objective thefulfillment of this need.

In addition, another objective of the present invention is to provide aplant growth regulator which, while delaying, retarding, and in somecases stopping plant height growth, has no significnt impact whatsoeveron the time until the plant flowers.

An even further objective of the present invention is to provide amethod and composition for general applicability to bedding plants andpotted flowering plants, which contains as its active ingredient,aminooxyacetic acid.

The method and manner of accomplishing each of the above objectives, aswell as others, will become apparent from the detailed description whichfollows.

DETAILED DESCRIPTION OF THE INVENTION

While aminooxyacetic acid has been suggested in the past as a possibleinhibitor of ethylene biosynthesis in plants, see HortScience 1980,15:238-243, and HortScience, 1981, 16:25-30, no one heretofore has everappreciated that this relatively inexpensive compound can be aneffective plant height growth regulator having widespread generalapplicability to bedding plants. Importantly, the use of aminooxyaceticacid also has no significant impact upon flowering of the plant. Itmerely retards plant height growth, which is, of course, a highlyfavorable effect.

Aminooxyacetic acid has the formula: ##STR1##

While it is possible that water soluble salts of aminooxyacetic acidwill have the same desirable effect as aminooxyacetic acid itself, todate testing has only been limited to aminooxyacetic acid per se.Nevertheless, it is within the range of predictability that watersoluble salts which are not harmful to the bedding plant would also beoperable, particularly Group I and Group II metal water soluble salts ofaminooxyacetic acid. It has been found in accordance with this inventionthat the timing of the application of the aminooxyacetic acid is also animportant aspect of the invention. In particular, in order to maximizeinhibition of plant growth, while at the same time having no significantimpact on plant flowering, the aminooxyacetic acid should be applieddirectly to the exterior of the plant when the plant is beyond itscotyledon or in other words, "seed leaf" stage. Next beyond the "seedleaf stage" is what is commonly referred to as "the number one stage",or in other words, the first true leaf stage. The optimum time forapplication is from about the first to the third true leaf stage. Mostpreferred is the second true leaf stage. It may be used at a highernumber of true leaves, if desired.

The most effective form for the aminooxyacetic acid is a water solution,and most preferably a water solution containing a wetting agent such asTween 20 or Triton X100 at a level of from about 0.05% to about 0.1% byweight of the wetting agent. Having wetting agents in the water solutionare desirable because this allows for better coverage on the leaf, or inother words, the active ingredient is allowed to spread more evenly andeffectively over the surface of the whole leaf. The precise wettingagent is not critical, so long as it is effective and not harmful to theleaf.

The concentration of active aminooxyacetic acid ingredient to providethe desired plant height growth inhibition should be from about 1millimolar to about 24 millimolar, preferably from about 4 to about 16millimolar. The preferred technique of application is to spray to runoff. For impatiens, the concentration should not exceed 12 millimolar.However, both the preparation form of the active ingredient and itsapplication form may be any suitable conventional one. The preferredpreparation form is, of course, liquid preparations contaning one ormore surface active or wetting agents.

The following examples are offered to further illustrate but not limitthe invention disclosed and clearly demonstrate the effectiveness ofaminooxyacetic acid in inhibiting plant height growth.

EXAMPLE 1

In this and the following experiments as well, a water solution ofaminooxyacetic acid contanin 0.01% of a wetting agent sold under themark Tween 20 and/or Triton X100, was simply sprayed to run off upon theabove ground portions of the below-described plants at the number 1stage, that is, the first true leaf stage. The concentrations were asspecified in each example below, and spray-on was accomplished with aconventional compression atomizer. The plants were all positioned inconventional plastic pots, 10 to 11 centimeters in diameter, and growingin a typical potted plant soil mixture. Cultivation was carried out in agreenhouse unless otherwise specified.

                  TABLE 1                                                         ______________________________________                                        The effect of aminooxyacetic acid on                                          controlling the height of petunias                                            grown from plug flats                                                                     Control  8 mM      16 mM                                                      (0 mM)   1*    2*      1*  2*                                     ______________________________________                                        Height.sup.x  13.2       9.5   8.2   8.3 7.4                                  (centimeters)                                                                 Days to flowering.sup.x                                                                     67         64    66    65  67                                   ______________________________________                                         *Number of applications (10 days                                              .sup.x Mean (50 plants per treatment)                                    

From the above, it can be seen that the average height of the plantstreated with the active ingredient was significantly reduced.Correspondingly, the days to flowering were not significantly changed.It is, therefore, shown from the data that aminooxyacetic acid is aneffective plant growth regulator for controlling the height of petuniasgrown from plug flats.

EXAMPLE 2

The aminooxyacetic acid formulation and method of application were asdescribed in Example 1. The plants were petunia `White Flash` grown inthe fall. The results are shown in the following table. It can be seenthat height was satisfactorily controlled at levels of applicationwithin the range of from about 8 mM per milliliter to about 16 mM.

                  TABLE 2                                                         ______________________________________                                        The effect of aminooxyacetic acid on                                          Petunia "White Flash" grown in the Fall                                       Control                                                                       (0 mM)        4 mM     8 mM    12 mM  16 mM                                   ______________________________________                                        Height.sup.z                                                                          6.9       6.8      4.5   4.0    2.5                                   Days to 66        67       68    65     66                                    flowering.sup.z                                                               ______________________________________                                         .sup.z Mean (12 plants/treatment).                                       

EXAMPLE 3

The effect of AOA on height retardation of Petunia `White Flash` grownin the spring was measured. The concentration and liquid composition ofthe active aminooxyacetic acid was as described in example 1. Table 3shows the results of the study.

                  TABLE 3                                                         ______________________________________                                        The effect of aminooxyacetic acid on height                                   retardation of Petunia White Flash grown                                      in the Spring                                                                 ______________________________________                                                2 mM         4 mM         8 mM                                                 1*    2*     3*    1*  2*   3*    1*  2*  3*                         ______________________________________                                        Height**                                                                              15.9   12.9   12.0 12.4 11.1 11.0 13.7 9.9 6.4                        Days to 67     65     68   68   66   64   67   65  67                         flowering.sup.y                                                               ______________________________________                                                12 mM        16 mM                                                             1*    2*     3*    1*  2*   3*                                       ______________________________________                                        Height**                                                                              11.3   9.3    5.3  10.0 10.0 7.8                                      Days to 64     66     68   63   65   66                                       flowering.sup.y                                                               ______________________________________                                        Control                                                                                          H.sub.2 O + HCl                                                                          H.sub.2 O + HCl                                         H.sub.2 O  (1 appl.)  (1 appl.)                                       ______________________________________                                        Height.sup.y                                                                          14.1       12.8       13.2                                            Days to 67         65         65                                              flowering                                                                     ______________________________________                                         *Number of applications applied at 10 day intervals.                          **Height in centimeters                                                       .sup.y Mean (10 plants per treatment)                                    

The data in the table show that AOA, when compared to the control,showed effective height retardation of Petunia `White Flash` grown inthe spring.

From the data shown in Examples 1 through 3 on petunia, it can be seenthat aminooxyacetic acid is an effective plant height growth inhibitorfor petunias and that it does not have any significant impact or delayon flowering.

The following Table 4 shows treatment of impatiens with a spray to runoff of the composition and at the second true leaf stage.

                  TABLE 4                                                         ______________________________________                                        The effect of AOA in controlling height,                                      diameter, and days to flower of impatiens                                     `Super Elfin Scarlet` grown in the fall.                                           Number of     Height.sup.y                                                                            Diameter.sup.y                                                                        Days to                                  mM   AOA Applications.sup.z                                                                      (mM)      (mM)    Flower                                   ______________________________________                                        0    1             34.39     69.64   75                                       4    1             33.44     38.44   84                                            2             27.50     37.92   85                                            3             22.46     36.34   87                                       8    1             29.17     40.27   84                                            2             22.20     37.11   87                                            3             24.28     29.41   85                                       12   1             13.84     48.47   89                                            2             15.94     39.71   90                                            3             10.61     19.11   93                                       ______________________________________                                         .sup.z Number of applications applied at 7day intervals.                      .sup.y Mean (18 plants per treatment)                                    

What is claimed is:
 1. A method of inhibiting bedding plant height growth without killing the plant, and without having any significant impact on flowering, said method comprising:spraying on the plant leaves of bedding plants to the point of run-off at a point in time when the plant is beyond the seed leaf stage, and approximately from about the first true leaf stage to the third true lead stage, from about 1 millimolar concentration to about 24 millimolar concentration of a solution of aminooxyacetic acid.
 2. The method of claim 1 wherein the aminooxyacetic acid is applied by spraying a water solution of aminooxyacetic acid.
 3. The method of claim 1 wherein the concentration is from about 4 millimolar to about 16 millimolar.
 4. The method of claim 2 wherein said solution contains a surface active wetting agent at a level of from 0.05% to about 0.1% by weight concentration. 